Bird Technologies 4412A - Manual (Page 23)

13
Performance Notes
The Series 4410 wattmeter is sensitive to the presence of amplitude modulated
signals and this can affect the accuracy. However, small amounts of AM (up to
10%) are tolerable, but for every 1% of AM, the inaccuracy of the reading may
increase by up to 1% beyond the rated accuracy. Use above 10% AM is not rec-
ommended. The stated accuracy does not include the effect of the less-than-
infinite directivity of the element used. This is generally insignificant except for
reflected power measurements where VSWR is low.
Although the Series 4410 Wattmeter is equipped with Quick-Change connector
types, it must be remembered that the power rating and insertion loss may be
affected if other connectors are used. Power limits must be governed by the
type of connector or transmission line used. For other types of Quick-Change
connectors, see Replacement Parts List.
When the range switch of the Series 4410 Wattmeter is set in one of the num-
bered positions; i.e., other than OFF or BATT, it is normal for the meter to drift or
deviate off the zero setting. This condition occurs when no element is in the line
section socket or if the element is rotated 90° in the line section to
a shorting
position.